1. Technical Field
The present invention relates to an image-reading apparatus and method.
2. Related Art
In an image-reading apparatus, there may be cases where, while a sheet which is an object to be read is being transferred, the sheet is unintentionally deflected or flexed. Upon occurrence of such flexural deformation (or irregularities), a distance between an image sensor such as a CCD (Charge Coupled Device) and a surface of the sheet varies from region to region on the sheet, which causes the magnitude of an output signal from the image sensor to vary among the regions of the sheet even though the sheet has uniform density on its entire surface. When flexural deformation occurs as described above, the output signal from the image sensor deviates from proper values that match the image densities of the sheet surface.
Conventionally, as measures to prevent the above-described flexural deformation during transfer, a guide face for guiding the sheet is provided to thereby mechanically reduce the occurrence of flexural deformation. However, because such mechanical measures are incapable of effectively preventing minute flexural deformation or other flexure, the mechanical measures are not necessarily satisfactory in preventing the occurrence of flexure.